Antibacterial Effect of Experimental Chlorhexidine-releasing Polymethyl Methacrylate-based Root Canal Sealers

Introduction: This study evaluated the extent of chlorhexidine release from experimental chlorhexidine-containing polymethyl methacrylate (PMMA)-based root canal sealers prepared from a methacrylate-based sealer (SuperBond Sealer, Sun Medical Co Ltd, Shiga, Japan) and to examine its antimicrobial effect against Enterococcus faecalis using the direct contact test. Methods: Chlorhexidine diacetate powder was mixed with PMMA powder of SuperBond Sealer to obtain chlorhexidine concentrations of 1 wt%, 2 wt%, and 3 wt%, respectively. PMMA disks were fabricated by self-curing the experimental PMMA powder and pure SuperBond sealer (control) and immersing them in distilled water at 37 °C for 12 weeks. Chlorhexidine release was analyzed by high-performance liquid chromatography. The direct contact test was performed on wells of 96-well plates coated with the respective experimental root canal sealers (n = 6). Bacterial suspensions were placed directly on the sealers that were aged for 12 weeks. Results: The cumulative chlorhexidine release after 12 weeks of water immersion was largely dependent on the amount of chlorhexidine powder that was initially incorporated into the PMMA-based sealer. Kruskal-Wallis test revealed that chlorhexidine concentration had a significant effect on the cumulative release (p = 0.0005). Experimental sealers with the incorporation of 2 wt% and 3 wt% chlorhexidine exhibited sustained antimicrobial effect for at least 4 weeks and 8 weeks. Conclusion: The incorporation of 2wt% and 3wt% chlorhexidine in the PMMA-based sealer had a long lasing antimicrobial effect against Enterococcus faecalis as a result of the turbidimetric determination of bacterial growth.